In the proposed study, our primary goal is to determine if older adults, as compared to younger adults, will be less able to recruit neural areas necessary for compensation during sleep deprivation on an attention task and a task of response inhibition. Tasks of visual spatial attention and response inhibition will be used, because they assess the functioning of two distinct networks particularly vulnerable to sleep loss. We specifically propose to use functional magnetic resonance imaging (fMRI) to investigate the effects of 36 hours of sleep deprivation on the neural response to both a visual spatial attention task and a task of response inhibition. Functional magnetic resonance imaging (fMRI) will be used to measure blood flow changes via the blood oxygen level dependent (BOLD) method. This method allows for the high spatial and temporal resolution necessary for these proposed investigations. Influence of age and task type will be examined to determine how sleep loss interacts with each of these factors to produce altered neural function and impaired performance.